1. Field of the Invention
Aspects of the present invention relate to an optical pickup device to read information recorded on an optical disk or to record new information on the optical disk.
2. Description of the Related Art
An optical pickup device is a device to read information recorded on an optical disk (such as a compact disk (CD), digital video disk (DVD), and a blu-ray disk (BD)) or to record new information on the optical disk by irradiating a laser beam onto the optical disk. If a focus of a laser beam irradiated onto a disk is deflected, the optical pickup device moves an objective lens in a radial direction of the disk or in an optical axis direction, thereby correcting the focus of the laser beam.
Korean Patent Laid-Open Publication No. 2006-0125193 discloses an example of an optical pickup device. The conventional optical pickup device comprises a lens holder on which an objective lens is mounted, a focus coil and a tracking coil coupled to the lens holder to move the lens holder in a radial direction of a disk or in an optical axis direction, magnets arranged close to the focus coil and the tracking coil, and a plurality of suspension wires to support the lens holder in a movable manner. Each suspension wire has one end fixed to the lens holder and another end fixed to another holder filled with gel. The suspension wire has a predetermined elasticity sufficient to movably support the lens holder.
In the conventional optical pickup device, a resonance frequency is determined based on a weight or a structure of the lens holder and properties (material, diameter, length, etc.) of the suspension wire used to fix the lens holder. Also, when designing a servo system to focus or to track the objective lens, the characteristics of the resonance frequency should be considered.
However, since the resonance frequency is a fixed value, the conventional optical pickup device does not compensate for an increase or a reduction in a rotation frequency of an optical disk drive. Specifically, an optical pickup device designed for a low-speed mode cannot easily be used for a high-speed mode, and an optical pickup device designed for a high-speed mode cannot easily be used for a low-speed mode. Moreover, if an optical disk drive operates at a higher speed than a predetermined speed, it causes significant disturbance as well as excessive deflection and eccentricity of an optical disk. Therefore, the optical pickup device may suffer from an unstable operation thereof.